This invention relates to a control device for spraying which is primarily but not exclusively intended for use with vehicles such as an all terrain vehicle (xe2x80x9cATVxe2x80x9d), small farm tractors, lawn tractors and the like.
It is known to provide a spray control system for ensuring that a correct spray application rate is maintained. Such a system will generally include a constant speed pump which pumps fluid to be sprayed from a holding tank to a spray boom having a series of spray nozzles. A valve means such as a butterfly valve or motor driven ball valve is provided in the main supply line between the tank and the boom. The valve means is operable to divert flow from the main supply line to a by-pass line so as to adjust the volume to the spray boom as may be required to achieve the application rate. A flow meter is provided to measure flow to the boom to enable the correct spray rate (usually measured in liters per hectare) to be achieved.
It is generally the case that a spray boom will have a plurality of set volume spray nozzles. After having determined nominal speed and application rate, the operator will select the necessary tip size. Generally, the nozzle tips are selected for optimum performance and therefore the tip size selected will be such that for the nominal speed and application rate the fluid flow through the nozzle tip will be at about midway in the performance range of the tip. Tip sizes are generally determined according to an international standard such as ISO 10625 or a national yet recognised standard such as BCPC.
Known spray control systems of this type are generally not suitable for spraying apparatus using 6, 12 or 24 volt DC pumps which are commonly used with eg smaller vehicles such as the now popular ATV. A flow meter is a high cost item as is the valving used to regulate the flow of spray fluid from the tank to the spray boom. This means that the system necessarily is of a cost greater than that which is justifiable for use with, for example, an ATV.
There is therefore a need for a low cost spray control system for use with vehicles such as an ATV yet is a system which at least includes the main features of bigger systems. The object of the present invention is to provide a low cost control device for spraying apparatus or at least provide the public with a useful choice.
According to one broad aspect of the invention, there is provided a spray control device for use with vehicle mountable spraying apparatus having a pump means for conveying fluid under pressure to a spray head, the control device including pressure sensing means for sensing the pressure of the fluid near the spray head, speed sensor means to enable calculation of vehicle speed, adjustment means for adjusting the delivery of fluid to the spray head and microprocessor means programmed to calculate from information derived from the pressure sensing means and speed sensor means a calculated spray application rate and compare same with a stored target application rate to thereby cause the adjustment means to, if necessary, adjust the pump means to deliver fluid so that a pressure is achieved such as to achieve the target application rate.